There has been a conventional optical head of such a type, in which a package of a semiconductor laser is exposed and is cooled by the wind pressure of wind due to the rotation of an optical disk as disclosed in Japanese Patent Public Disclosure No. 2-240839/1994 Official Gazette.
However, such a heat radiation technique employed in the conventional optical head is not effective for the following reasons. Namely, there is a limit to the area of the exposed package. Further, the semiconductor laser is very likely to collide with the optical disk, because it is necessary for utilizing the wind pressure of wind caused by the rotation of the optical disk to bring the semiconductor laser very close to the optical disk. Moreover, the wind caused by the rotation of the optical disk is weak in itself and thus has little effect on the heat radiation in the case of using a low revolution optical disk. Consequently, the conventional optical head has a problem in that the characteristics of a signal is degraded owing to heat produced in the semiconductor laser and a laser optical system. Furthermore, an optical head equipped with a high output semiconductor laser for the purpose of recording and reproducing information can not be developed. Additionally, practical uses of the conventional optical head have been limited to a read-only compact disk (CD) player.
The present invention is accomplished to eliminate the drawbacks of the conventional optical head.
Accordingly, a main object of the present invention is to obtain a heat-radiating and/or cooling structure which is more efficient by far than that of the conventional optical head, to avoid increase in weight of a movable part involved in such a heat radiation structure and to improve the control characteristics of an actuator.